Rearview mirror assembly for a vehicle

ABSTRACT

An interior rearview mirror assembly for a vehicle comprises an electro-optic mirror unit whose reflectivity is variable in response to an electrical voltage applied thereto. The mirror unit includes a first substrate and a second substrate with an electro-optic medium sandwiched therebetween. The second substrate includes a recess at a perimeter region thereof. The mirror assembly includes at least one light sensor disposed behind the first substrate of the mirror unit and generally at the recessed perimeter region of the second substrate. The at least one light sensor is operable to receive light through the first substrate and unobstructed by the second substrate of the mirror unit. The light may be received through a bezel of the mirror assembly and through the first substrate and unobstructed by the second substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/498,420,filed Aug. 3, 2006, entitled A REARVIEW MIRROR ASSEMBLY FOR A VEHICLE,by Lawlor et al., now U.S. Pat. No. 7,209,278, which is a continuationof U.S. patent application Ser. No. 10/512,206, filed Oct. 22, 2004, nowU.S. Pat. No. 7,110,156, which corresponds to PCT/IE03/00059, whichclaims priority of Irish patent application No. S2002/0545, filed Jul.1, 2002, and Irish patent application No. S2002/0314, filed Apr. 26,2002, the disclosures of which are hereby incorporated by referenceherein.

The present invention relates to rearview mirror assemblies, for exampleelectro-optic rearview mirror assemblies in which two glass platessandwich an electro-optic medium.

Electro-optic rearview mirrors are well known in the art; see forexample U.S. Pat. Nos. 5,140,455, 5,151,816 and 5,659,423 and thefollowing paper: N. R. Lynam, “Electrochromic Automotive Day/NightMirrors”, SAE Technical Paper Series, (870636) (1987).

Brackets for supporting rearview mirrors are well known in the art; seefor example U.S. Pat. Nos. 4,936,533, 5,058,851, 4,524,941 and4,012,022. Rearview mirrors in many instances are mounted to thebrackets by means of a ball and socket connection.

Electro-optic and in particular electro-chromic (EC) mirrors are now ingeneral usage in vehicles at the upper end of the market. The EC mirrorsare relatively expensive and their cost can make them prohibitive formotor vehicles at the medium and lower end of the market. Such ECmirrors however confer considerable advantages over known prismaticmirrors and it is therefore desirable to reduce the cost of productionof electro-optic mirrors so that they can be used in a broad range ofvehicle types.

There is therefore a need for a rearview mirror that is economical toproduce but which meets the expectations of the automobile market interms of functional performance such as vibration, safety regulations,ease of assembly at an auto company in terms of bracket mounting,electrical connections and reliability.

These objects are achieved by the inventions claimed in one or more ofthe appended claims.

Embodiments of the invention will now be described, by way of exampleswith reference to the accompanying drawings, in which:

FIG. 1 is a front perspective view of a rearview mirror assemblyaccording to one embodiment of the invention.

FIG. 2 is a rear perspective view of the mirror assembly of FIG. 1.

FIG. 3 is a rear view of the interior of the mirror of FIG. 1.

FIG. 4 is a cross sectional view of the mirror of FIG. 3 taken along theline A-A.

FIG. 5 is a rear perspective view of the mirror of FIG. 1 with thehousing removed.

FIGS. 6 and 7 are cross sectional views of the mirror of FIG. 1.

FIG. 7 a is an exploded rear perspective view of the mirror of FIG. 1.

FIGS. 8 and 9 are rear perspective views of another embodiment of theinvention, omitting the mirror housing.

FIG. 10 is a side view of the mirror unit and bracket of FIGS. 8 and 9.

FIG. 11 is a cross sectional view of the mirror unit and bracket ofFIGS. 8 and 9 taken on the line A-A of FIG. 10.

FIG. 12 is a front perspective view of another embodiment of rearviewmirror assembly according to the invention.

FIG. 13 is a exploded rear view of the rearview mirror assembly of FIG.12.

FIG. 14 is a exploded front view of the rearview mirror assembly of FIG.12.

FIG. 15 is a cross-sectional view of the mirror unit and support arm ofthe assembly of FIG. 12 taken on the line A-A of FIG. 16 a.

FIG. 16 is a cross-sectional view of the mirror assembly of FIG. 12taken on the line B-B of FIG. 16 a.

FIG. 16 a is a front view of the rearview mirror assembly of FIG. 12.

FIG. 17 is a rear perspective view of part of another embodiment of theinvention.

FIGS. 18( a)-(d) are schematic diagrams illustrating large area sheetsof glass from which individual front and rear glass plates used inelectro-optical mirror units are cut.

FIG. 19 is a rear perspective view of a still further embodiment of theinvention, omitting the housing and bezel.

FIG. 20 is an exploded view of the embodiment of FIG. 19, omitting thebracket.

FIG. 21 shows the rear side (i.e. the side facing the backplate) of thePCB of FIGS. 19 and 20, omitting all the circuitry except the lightsensors and contact strips.

FIG. 22 is a plan view of a phosphor bronze lead frame embedded in thebackplate of the embodiment of FIGS. 19 and 20.

FIGS. 23( a) to 23(c) are various perspective views of the supportbracket of the embodiment of FIGS. 19 and 20.

FIG. 24( a) is a side view of the bracket of FIG. 23.

FIG. 24( b) is a cross-section of the bracket of FIG. 23 taken on theline A-A of FIG. 24( a).

FIG. 24( c) is a cross-section of the bracket of FIG. 23 taken on theline B-B of FIG. 24( b).

FIGS. 25( a) and 25(b) are perspective views of a further embodiment ofbracket which could be used in the embodiment of FIGS. 19 and 20.

FIG. 26 is a perspective views of a still further embodiment of bracketwhich could be used in the embodiment of FIGS. 19 and 20.

As will be described in more detail, electro-optic mirror units comprisefront and rear glass plates with an electro-optic medium sandwichedbetween them. The glass used in these units is highly specialised andexpensive, and since the front and rear glass plates of an electro-opticmirror unit constitute a significant proportion of the costs of theoverall mirror assembly it is very important to try to minimise wastageof glass from the plate glass from which the mirror glass profiles arecut. However, the problem is complicated by the fact that thetransparent front TEC glass is provided in sheets of a different widthfrom the sheets of the reflective rear ITO(Ag) glass, TEC and ITO(Ag)glasses being commercially available types of glass used inelectro-optic mirror construction.

Referring initially to FIG. 18, FIG. 18( a) shows the number (204) offront glass plates conventionally cut from a standard sheet of TEC glassmeasuring 3352.8 mm×1219.2 mm, each glass plate being 249.5 mm wide by65.7 mm high. By contrast, FIG. 18( b) shows the number (252) of frontglass plates which may be produced from the same standard size sheetwhen each front glass plate is 219.4 mm wide and 61.5 mm high. Thisrepresents a 23% increase in the number of front glass plates availablefrom the standard TEC glass sheet. Similarly, FIG. 18( c) shows thatonly 60 standard sized 249.5 mm wide by 65.7 mm high rear glass platescan be cut from a standard 1700 mm by 750 mm sheet of ITO(Ag) glass,whereas FIG. 18( d) shows that 77 rear glass plates of size 219.4 mmwide and 61.5 mm high can be cut from the same ITO(Ag) glass sheet. Thisrepresents a 28% increase in the number of rear glass plates availablefrom the standard ITO(Ag) glass sheet.

It has therefore been discovered that optimum usage of both the frontand rear glass sheets is obtained by using front and rear mirror glassplates of size 219.4 mm by 61.5 mm. These are therefore the sizes offront and rear glass plates used in the various embodiments, exceptwhere otherwise noted. This minimises wastage and leads to optimum costefficiency. In determining these sizes it has also been determined thatin terms of a low cost electro-optic mirror the size of the mirror faceis in fact larger than the average size of a prismatic type mirror face.Thus, the invention not only provides optimum efficiency in terms ofglass usage and thus cost reduction by minimising wastage, but it alsoprovides, a larger more effective mirror than the prismatic type mirrorwhich it will replace.

Referring now to FIGS. 1 to 7 and 7 a, a rear view mirror assembly 20comprises a housing 21 containing an electro-optic mirror unit 22, abezel 23 which retains the mirror unit 22 in the housing, the mirrorunit 22 being located just behind the bezel 23 and being viewablethrough the opening in the bezel, and a support bracket 30 for attachingthe assembly to the interior cabin of a vehicle, for example to the topof the windscreen or the header. In the present embodiment the upper endof the bracket 30 is adapted for sliding engagement with a mirror mount100, often referred to as a “button”, which is adhesively attached tothe interior surface of the windscreen in known manner.

Electro-optic mirror units are well-known in the art and typicallycomprise front and rear glass plates 22 a, 22 b respectively (FIG. 7)with a layer of an electro-optic medium (not shown) sandwiched betweenthem. The front plate 22 a is transparent and the rear plate 22 b has alayer of silver or other reflective material on its inside surface. Theunit 22 is positioned in the housing 21 with the front plate 22 aexposed through the bezel opening so that the reflective layer on therear plate 22 b is viewed through the front plate and the layer ofelectro-optic medium. The inside surface of each plate bears anelectrically conductive electrode layer, the electrode layer on thefront plate being transparent and the electrode layer on the rear platealso being transparent, at least if it is in front of the reflectivelayer (alternatively the reflective layer may also constitute theelectrode layer for the rear plate so avoiding the need for a separateelectrode layer on the rear plate). The light transmissivity of theelectro-optic medium, and hence the reflectivity of the mirror unit, canbe varied by the application of a variable control voltage across theelectro-optic medium, i.e. across the conductive electrode layers on theinside surfaces of the plates. The electro-optic medium may comprise anymaterial, for example electro-chromic or liquid crystal, which has thedesired electro-optic properties.

The electro-optic mirror unit 22 is preferably an electro-chromic (EC)cell either of the solid state type or electrochemichromic type, but maybe any desired form of cell. In the present embodiments the mirror unit22 is an EC cell whose front plate 22 a comprises TEC glass and whoserear plate 22 b comprises ITO(Ag) glass. The electro-optic mediumsandwiched between the plates 22 a, 22 b is a self-supporting solidpolymer matrix (SPM). The construction of EC cells is well known in theart and is described for example in the prior art documents noted aboveor in U.S. Pat. No. 5,572,354 the contents of which are incorporatedherein by reference. However, this and following embodiments are notlimited to the use of any particular types of glass, any particular typeof electro-optic medium or any particular type of electro-optic mirrorunit.

The front and rear plates 22 a, 22 b are the same size (except for arecess 25, FIG. 7 a, provided in the bottom edge of the rear plate 22 bfor a purpose to be described) but have a small vertical offset, so thatthe upper edge of the rear plate 22 b projects slightly above the upperedge of the front plate 22 a, and correspondingly the lower edge of thefront plate 22 a projects slightly below the lower edge of the rearplate 22 b. This offset is clearly seen in FIGS. 6 and 7. The reason forthe offset is to expose a narrow strip of the conductive electrode layeron the inside surface of the rear plate 22 b at the top of the mirrorunit and a corresponding narrow strip of the conductive electrode layeron the inside surface of the front plate 22 a at the bottom of themirror unit. These exposed strips are electrically connected toconductive electrode contacts 38 and 39 respectively which areessentially elongated toothed clips having a generally U-shaped crosssection and which clip over the exposed edges of the rear and frontplates respectively.

The EC cell 22 is securely fixed by adhesive, clips or other suitablemeans to a non-conductive backplate 31 moulded, for example, forglass-filled polypropylene (PP) or nylon. A socket member 32 is mountedon the opposite side of the backplate 31 to the cell 22, i.e. on therear side of the backplate, and is preferably formed integrally with thebackplate. A dependent portion 33 of the bracket 30 forms acorresponding ball member. The ball and socket members 33, 32interengage to form a pivot assembly, FIG. 6, such that a part-sphericalexternal surface 33 a of the ball member 33 is rotatable within acomplementary part-spherical internal surface 32 a of the socket memberto allow a range of angular movement of the mirror unit relative to thebracket 30. The bracket 30 is preferably moulded from a differentmaterial to the backplate 31. For example, the bracket 30 can be mouldedof nylon and the backplate of PP, or vice versa.

A printed circuit board (PCB) 34 includes an electrical circuit forcontrolling the operation of the EC cell 22, in particular by varyingits reflectivity in response to the signals from a pair of light sensors26 and 27 (e.g. photodiodes or phototransistors) which are mounted on,but dependent via pairs of rigid conductors 26 a and 27 a from, the PCB.The PCB 34 is fixed by adhesive, clips or other suitable means to therear side of the backplate 31, the electrical circuit being on the sideof the PCB facing the backplate and therefore not visible in thedrawings.

The backplate 31 has electrical contacts 36, 37 electrically connectedto the electrode contacts 38, 39 of the EC cell. Contact pads 40 (FIG.5) on the PCB 34 are connected to respective ones of the contacts 36, 37and the electrical circuit on the PCB 34 supplies the variable controlvoltage across the EC cell 22 via the pads 40. A wire harness 41provides a power supply to the PCB 34 from the vehicle power supply. Thearrangement of the contact pads 40 and contacts 36, 37 eliminates theneed for soldering, making the product easier to assemble. The preferredsizes of the front TEC glass and rear ITO(Ag) glass plates as referredto above results in a reduced size requirement for the electrodes 38, 39of around 15% with consequent cost savings.

The backplate 31 has a boss 45 incorporating flared apertures 46, 47(FIG. 4) for accommodating the light sensors 26, 27 respectively. Thelocation of the sensors 26, 27 in the boss 45 provides very significantmechanical protection for the sensors and since the surface 50 of thefront glass plate 22 a is conductive an electrical path is available fordischarge of electrostatic and other non-desirable electrical charges.Since the sensors 26, 27 are disposed rearwardly of the silvered rearglass plate 22 b the bottom edge of the latter has a recess 25 relativeto the front glass plate and the boss 45 is located in register with therecess 25. Thus the sensors 26, 27 are able to receive light through thefront transparent glass plate 22 a unobstructed by the rear glass plate22 b. The sensors 26, 27 face in the same direction in the boss 45, i.e.normal to the mirror unit 22 and generally facing the rear of thevehicle when the mirror assembly is mounted in the vehicle cabin forrearview viewing.

The bezel 23 has respective apertures 23 a, 23 b in front of the flaredapertures 46, 47 in the boss 45. The bezel aperture 23 b is locateddirectly in front of the flared aperture 47 and sensor 27 so that thelatter detects light directed along an axis generally normal to the ECcell 22. However, the bezel aperture 23 a is laterally offset relativeto the sensor 26 which, together with the skewed aspect of the flaredaperture 46 seen in FIG. 4, ensures that the sensor 26 detects lightdirected laterally from one side of the axis normal to the cell, i.e.from the direction V, despite facing in the same direction as the sensor27.

In use, when the mirror assembly is mounted for rearward viewing in theinterior cabin of a vehicle, the sensor 27 senses light from the rear ofthe vehicle generally along a longitudinal axis of the vehicle while thesensor 26 senses light from the rear of the vehicle but obliquely to theright or to the left of the longitudinal vehicle axis. In particular,the sensor 26 senses light from a passenger or driver side window of thevehicle. Thus the sensor 27 acts as a glare sensor, since it isresponsive to, for example, the glare from following headlamps, whilethe sensor 26 acts as an ambient sensor, since it is responsive to thegeneral level of illumination outside the vehicle.

With both ambient and glare sensors facing rearwardly in the bezel 23the housing 21 does not need to have an aperture for the ambient sensor26, which conventionally faces forwardly.

The backplate 31 is also provided with resilient members 51 which abutand engage flanges 52 on the inside of the housing 21 and providerigidity and assist in vibration minimization. This constructioneliminates further components while maintaining a support function.

The direct connection between the bracket 30 and the backplate 31, whichitself is directly fixed to the EC cell 22, improves the stiffness ofthe assembly that leads to an improvement in the vibration performanceof the mirror and thus allows for the use of an all-plastic bracketsupport 30 which is a major reduction in the cost of the product. Thisalso means that the mirror housing 21 is not required as a structuralcomponent and principally serves as a cosmetic shroud around the mirrorunit. This allows a low cost plastic such as PP to be used. As stated,the PCB 34 clips onto the back plate 31 and has the glare sensor 27 andthe ambient sensor 26 located together on the PCB 34. Thus the ambientsensor 26 does not need to extend through the rear of the mirror housing21 and allows for the PCB 34 to be reduced in size and hence enables acost reduction in the PCB. Since the backplate contains a support boss45 for the sensors, this eliminates the need for other sensor supportsand hence a reduction in the component count is achieved.

One of the advantages of the above embodiment is that the glare andambient light sensors are configured so as to view via apertures in thebezel portion of the mirror assembly. This is particularly useful whenadditional accessories (such as are disclosed in U.S. Pat. Nos.6,124,886, 6,245,262 and 6,222,460, the entire disclosures of which arehereby incorporated by reference herein) are included in the cavity ofthe mirror housing. By configuring both sensors to view viabezel-located apertures/view-ports, additional accessories/structurescan be accommodated within the mirror housing cavity without concern foroccluding a field of view of either sensor.

Rather than having a recess 25, the rear glass plate 22 b may have aportion of its reflective coating removed to enable positioning of thelight sensors and the bezel in register with the area of reflectivecoating which is absent. Alternatively, the rear glass plate can have atransflective portion such as is disclosed in U.S. Pat. No. 5,910,854,the entire disclosure of which is hereby incorporated by referenceherein.

Furthermore, microlouvers or angle-of-incidence-transmission-dependentfilms such as are available from 3M could enable the sensor 26 toreceive ambient light that is incident at an angle to the vehicle'slongitudinal axis despite the sensor 26 facing in the same direction asthe glare sensor 27. Alternatively, off-axis ambient light can bedirected to the sensor 26 via a light pipe.

The above mirror assembly can be provided as an assembled kit butwithout the housing 21 (i.e. essentially as seen in FIG. 5). Such kitwould comprise an EC cell, a PCB (including EC cell drive circuitry), abackplate, first and second light sensors, a bracket, and a bezel withfirst and second apertures therein, with the second aperture thatcorresponds to the second or ambient light sensor being so located whenthe kit is married to a mirror housing during assembly of the completeinterior mirror assembly, the second photo sensor views sideways fromthe mirror assembly when it is mounted in the vehicle cabin, i.e.towards a driver-side or passenger-side front side window. Thisfacilitates assembly of such kits in a central manufacturing location,and then their shipment to remote mirror assembly plants located, forexample, overseas, where the assembled kit is married with alocally-made mirror housing, any additional accessories and an(optionally) locally-made mirror mount to form a complete interiorrearview mirror assembly. Alternatively, the kit need not be assembledprior to shipment, and the entire assembly from the component partscould take place at the final mirror assembly site.

FIGS. 8 to 11 show another embodiment of the invention. In thisembodiment similar numerals have been used for like parts as in theprevious embodiment and only the differences between this embodiment andthe embodiment of FIG. 1 will be described. In FIGS. 8 to 11 the housing21 and bezel 23 are not shown.

In this embodiment only one light sensor 60 is used which integratesboth the glare and ambient functions and this single sensor 60 islocated in a boss 61 on the backplate 31 and will look through a singleaperture (not shown) in the bezel 31.

In this embodiment electrical contacts 70, 71 are moulded into the ballmember 33 and electrical contacts 72, 73 are moulded into the socketmember 32. A portion of each of the contacts 70, 71 is exposed on thepart-spherical external surface 33 a of the ball member 33 and a portionof each of the contacts 72, 73 is exposed on the part-spherical internalsurface 32 a of the socket member 32. The orientation and positions ofthe portions of the electrical contacts 70-73 disposed on thepart-spherical surfaces 32 a and 33 a is such that over a range ofangular movement of the mirror unit 22 the contact 70 is in slidingengagement with the contact 72 and the contact 71 is in slidingengagement with the contact 73.

The contacts 70, 71 extend upwardly in the ball member 33 to the upperend of the bracket 30 for making electrical contact with the vehicleelectrical supply. The contacts 72 and 73 in the socket member areelectrically connected, by connectors not shown, to the PCB 34 atcontacts 74, 75 respectively. The sliding engagement of the contacts 72,73 with the contacts 70, 71 respectively, and the connection of thecontacts 72, 73 with the PCB contacts 74, 75, supplies electrical powerfrom the vehicle power supply to the PCB 34. This arrangement eliminatesthe need for a separate wire harness which reduces costs and enables themirror to be assembled more easily.

In this embodiment the backplate 31 incorporates plastic tabs 96 whichare coated with a conductive material, the conductive coating extendingin a strip 98 along the bottom edge of the backplate 31 and beingelectrically connected to the PCB 34 in the region of the boss 61. Theconductive tabs 96 resiliently press against the conductive surface ofthe front glass plate 22 a to provide an electrical connection from thePCB 34 to the front glass plate 22 a of the electrochromic cell 22. Thisdesign eliminates one electrode strip 39 off the EC cell 22 and resultsin a saving of around 54% of the cost of the electrode 39.

FIGS. 12 to 16 and 16 a show a further embodiment of the invention. Inthis construction, the backplate 31 of the previous embodiment is notused and the PCB 34 is fixed by adhesive, clips or other suitable meansdirectly to the rear plate 22 b of the EC cell 22. Furthermore, only asingle light sensor 80 is provided, in this embodiment near the top ofthe EC cell, a small area 81 of the reflective layer on the rear glassplate 22 b being removed in register with the sensor 80 to allow thesensor to view through the transparent front glass plate 22 a.Alternatively, the top edge of the rear glass plate 22 b could berecessed, in a similar manner to that previously described for therecess 25 in the bottom edge, and the sensor 80 aligned with the recess.The PCB 34 is electrically connected to the top edge of the conductiveelectrode layer on one of the glass plates 22 a, 22 b of the EC cell 22by an electrical contact 90.

In the case where the edge of the cell 22 has a conductive material itis sufficient for the contact 90 to abut the edge of the cell. In thecase where the edge of the cell does not have a conductive material itis necessary for the contact 90 to be engaged or partly located betweenthe front and rear glass sheets so as to make electrical connection withthe relevant conductive electrode layer. The contact 90 is located inplace during manufacture of the cell, and it is noted in this embodimentthat the contact 90 may be a conductive tape foil or layer. A similararrangement (not shown) is used at the bottom of the cell to makeelectrical contact with the conductive electrode layer on the other ofthe glass plates of the EC cell 22.

In this embodiment, due to the absence of the backplate 31, the socket32 is moulded into the rear of the housing 21, but the same arrangementof slidably engaging electrical contacts 70, 71 and 72, 73 are providedon the ball member 33 and the socket member 31 respectively aspreviously described. At the inner surface of the socket 32 resilientelectrical contacts 92, connected to the contacts 72, 73 respectively,engage respective electrical contacts 93 on the PCB 34 to provide anelectrical connection between the power supply contacts 70, 71 and thePCB 34.

It will be noted from FIG. 15 that in this embodiment the front and rearglass plates 22 a, 22 b of the EC cell 22 are positioned in strictregister with no vertical offset as is seen, for example, in FIGS. 6 and7. This means that the height of the mirror can be greater than that inthe previous embodiments leading to an even better product. In theembodiment of FIGS. 1 to 7 the height of the glass sheets is 61.5 mm andthe visible height of the mirror glass to the vehicle driver is 53 mm.In the present embodiment the height of the glass is 59 mm and becausethere is no offset in the front and rear glass plates the height of thevisible mirror is again 53 mm. Thus, less glass is used in thisconstruction because of the lack of offset in the front and rear glassplates of the EC cell 22. In this case the number of TEC glass plates isincreased by 25% and the number of ITO(Ag) glass plates is increased by40% as compared with existing mirrors. Alternatively, if the height ofthe glass is maintained at 61.5 mm, the visible height of the mirrorwould be 2.5 mm greater at 55.5 mm leading to an even better product. Inthis embodiment therefore, the cost can be reduced further or the sizeof the product can be increased because of the absence of overlappingglass sheets. Also the cost of providing the electrodes 38, 39 used inthe previous embodiments is eliminated.

It will be seen from FIGS. 15 and 16 that the housing 21 has no separatebezel 23, but rather the bezel 23 is integral with the main body of thehousing 21. The integral bezel 23 defines a mirror viewing opening 23 bwhich is slightly smaller than the lateral dimensions of the EC cell 22,as seen in FIG. 15. Therefore, in order to insert the EC cell 22 intothe housing 21 the latter is warmed sufficiently to the resilientlysoften the housing polymeric material (e.g. PP or nylon) but notsufficiently for the housing to lose its structural integrity. Then theEC cell 22 is inserted behind the bezel 23 while the housing 21 is stillwarm so that the edge of the EC cell is located in and gripped by ashallow recess 21 a of the housing just behind the bezel. Thereafter thehousing is allowed to cool and become rigid. This method of assembly hasthe advantage that a separate bezel is not required and the number ofparts is reduced.

However, due to the need to get the EC cell 22 through the front openingin the housing 21, the lateral dimensions of the opening are onlyslightly less than the lateral dimensions of the EC cell. This meansthat in the assembled mirror the bezel overlaps the edges of the EC cellby only a small amount, typically 1.5 mm. This exposes the black epoxylacquer seal which is conventionally coated around the edges of theglass plates and which extends partially onto the front surface of thefront glass panel as a narrow strip several mm wide adjacent the edge.The exposed part of this seal, i.e. the part of the strip not covered bythe bezel, will provide a cosmetic effect which can appear to the driveras part of the bezel itself.

FIG. 17 shows part of another embodiment of the invention in which theelectrical contact 36, 37 are in the form of a conductive adhesive tapeor coating for electrical connection to electrical contacts 40 on thePCB 34. This embodiment is a kind of hybrid of the embodiments of FIGS.8-11 and 12-16, since it has a single sensor 60 like the embodiment ofFIGS. 8-11 but the PCB 34 is mounted directly on the rear of the EC cell22 like the embodiment of FIGS. 12-16. Alternatively there may be twolight sensors as shown in relation to FIGS. 1-7. It wall be appreciatedthat the embodiment of FIG. 17 will have a housing 21 similar to that ofFIGS. 12-16, i.e. the socket member 32 will be moulded to the rear ofthe housing.

FIGS. 19 to 24 show another embodiment of the invention. In thisembodiment similar numerals have been used for like parts as in theprevious embodiment. In FIGS. 19 to 24 the housing 21 and bezel 23 arenot shown, but may be fitted as described for the embodiment of FIGS. 1to 7.

As in the first embodiment, in the present embodiment the EC cell 22 issecurely fixed by adhesive, clips or other suitable means to anon-conductive backplate 31 moulded, for example, from glass-filledpolypropylene (PP) or nylon. A socket member 32 is mounted on theopposite side of the backplate 31 to the cell 22, i.e. on the rear sideof the backplate, and is preferably formed integrally with thebackplate. The socket member 32 engages with the ball member 33 of asupport bracket 30 to allow angular adjustment of the EC cell 22. ThePCB 34 is fixed by adhesive, clips or other suitable means to the rearside of the backplate 31, the electrical circuit being on the side ofthe PCB facing the backplate and therefore not being visible in FIGS. 19and 20.

An electrically conductive lead frame 101, FIG. 22, is embedded in thebackplate 31. The lead frame 101 is stamped from a flat phosphor bronzesheet and is embedded into the backplate 31 by moulding the latteraround it, leaving certain contact and biasing fingers free of themoulded material as will be described. The lead frame comprises fiveelectrically isolated portions A, B C, D and E (in actual fact, for easeof handling the four portions are initially joined by narrow bridges ofphosphor bronze in the initial stamping but these are severed during orafter the moulding process to isolate the four portions). The electricalfunctions of the five portions of the lead frame are:

Portion A: Power supply +12v

Portion B: Ground

Portion C: EC cell anode (+ve)

Portion D: EC cell cathode.

Portion E: Heat Sink.

The EC cell cathode can be −ve or ground, and in the latter case thelead frame portions B and D can remain connected within the lead frameto provide one large ground plane providing substantial EMC protection.

The lead frame fingers which are left free of and thus extend out of themoulded material of the backplate 31 are as follows (see also FIGS.19-21):

-   -   Spring contacts 102 a, 102 b which are bent upwardly out of the        plane of the lead frame to bear resiliently against respective        electrical contacts 134 a, 134 b on the ball member 33. These        connect respectively to power (+12v) and ground of the vehicle        electrical supply via the bracket 30 as will be described.    -   Spring contacts 104 a, 104 b which are bent upwardly out of the        plane of the lead frame to bear resiliently against respective        electrical contacts strips 106 a, 106 b (FIG. 21) on the side of        the PCB 34 facing the backplate 31. These transfer the power and        ground of the vehicle electrical supply to the PCB 34 via the        lead frame portions A and B.    -   Spring contacts 108 a, 108 b which are bent upwardly out of the        plane of the lead frame to bear resiliently against respective        electrical contacts strips 110 a, 110 b (FIG. 21) on the side of        the PCB 34 facing the backplate 31. These receive the EC cell        anode and cathode voltages from the PCB 34 for control of the EC        cell reflectivity.    -   A spring contact 108 c which is bent upwardly out of the plane        of the lead frame to make large area contact with the PCB 34 to        dissipate heat from copper tracks and heat generating components        on the “hottest” area of the PCB. The portion E thereby        constitutes an efficient heat sink.    -   A plurality of contact fingers 112 (the outer pair of each group        of three seen at the bottom of FIG. 22) which are bent through        90 degrees at their outer ends to engage the conductive        electrode layer on the inside surface of the front glass plate        22 a (the front and rear glass plates 22 a, 22 b are slightly        offset as in the first embodiment). These apply the EC cell        anode voltage from the contact 108 a via the lead frame portion        C.    -   A pair of contact fingers 114 which are bent through 90 degrees        at their outer ends to engage the conductive electrode layer on        the inside surface of the rear glass plate 22 b. These apply the        EC cell cathode voltage from the contact 108 b via the lead        frame portion D.    -   A plurality of spring fingers 116 which are bent out of the        plane of the lead frame from the portions B, C and D to bear        resiliently against the interior of the mirror housing 21 (not        shown) to stabilise the EC cell 22 within the housing (at the        bottom of the lead frame the spring fingers 116 are the centre        fingers of each group of three).

This embodiment again uses ambient and glare light sensors 26, 27although in this case they are surface mounted on the PCB 34 rather thandepending from it. As before, the glare sensor 27 faces rearwardly ofthe vehicle when the mirror is mounted in the vehicle cabin and viewsthrough the transparent front glass plate 22 a of the EC cell via arecess 25 in the edge of the rear glass plate 22 b. However, the ambientsensor 26 in this case faces forwardly (relative to the vehicle) andviews forwardly of the vehicle through an aperture 120 in the PCB 34 anda corresponding aperture (not shown) in the mirror housing. When the PCB34 is mounted on the backplate 31 the sensors 26 and 27 sit inrespective apertures in a housing 122 moulded to the backplate 31, thehousing both mechanically protecting the sensors and shielding them fromextraneous light. Alternatively, a single light sensor may be positionedso that it is shrouded from stray light by a feature of the backplate,receives glare light though an aperture in the bezel and through therecess in the rear glass and receives ambient light from the oppositedirection through a hole in the PCB and an aperture in the mirrorhousing. This one sensor can monitor both ambient and glare lightlevels. Where two sensors are used, mounting them close together on thePCB 34 reduces adverse EMC effects by eliminating long conductive linesbetween the sensors.

The bracket 30, FIGS. 23 and 24, is (except as noted below) moulded fromglass-filled polypropylene (PP) or nylon. It has an upper end withinternal rails 124 for sliding engagement with a “button”-type mirrormount 100 for attachment of the bracket to the interior surface of avehicle windscreen in conventional manner. The bracket 30 furtherincludes a ball member 33 which depends from the upper end of thebracket and has a part-spherical external surface 33 a rotatable withina complementary part-spherical internal surface 32 a (FIG. 20) of thesocket member 32 to allow a range of angular movement of the EC mirrorunit 22 relative to the bracket 30.

The ball member 33 comprises a central cylindrical bore 126 and acylindrical body 128 of electrically insulating material extending fullythrough the bore 126 from the upper end of the bracket and terminatingin an exposed convex surface 130 below the lower end of the bore. Thebody 128 comprises three parts: two outer generally semi-cylindricalparts 128 a, 128 b separated by a central planar part 128 c. At theupper end of the bracket the parts 128 a, 128 b have respective integralspring arms 132, and at the lower and of the body 128 all three partscollectively define the convex surface 130.

The outer surfaces of the semi-cylindrical parts 128 a, 128 b are platedwith an electrically coating, the coating on each part extending ontothe convex surface 130 to form respective electrical contacts 134 a, 134b and from there each coating extends continuously along the length ofthe part 128 a or 128 b to the upper end of the bracket and onto the topsurface of the respective spring arm 132. Thus a direct electrical pathis made from each electrical contact 134 a, 134 b on the convex surface130 to a respective one of the spring arms 132. The central part 128 c,which is not conductively coated, prevents any short circuit between thetwo paths.

When the upper end of the bracket 30 is mounted to a mounting button 100the spring arms 132 engage conductive tracks (not shown) on the insidesurface of the windscreen, such tracks providing vehicle power andground which are thereby transferred to the respective contacts 134 a,134 b via the conductive coatings on the sides of the body 128. Thecontacts 134 a, 134 b are slidingly engaged by the lead frame springcontacts 102 a, 102 b over a range of angular movement of the EC cell 22for supplying power to the PCB 34 from the vehicle electrical system.

The body 128 may be manufactured in three pieces 128 a, 128 b and 128 cwhich are slid side-by-side into the bore 126 as indicated for the part128 b in FIG. 23( a). In such a case the outer parts 128 a and 128 b arepreferably hollow (as shown for the part 128 b) and individually mouldedof polysulphide or other electroplatable material and subsequentlyplated with conductive coatings. The centre part 128 c can be moulded ofthe same material but left unplated, or it can be moulded, like the restof the bracket 10, of a polymeric material such as PP or nylon. However,a two-shot moulding process may be used. In the first shot, the centralpart 128 c is moulded using a material which cannot be electroplated.Then, in the second shot, the outer semi-cylindrical parts 128 a and 128b are moulded to opposite sides of the centre part 128 c but using amaterial such as polysulphide which can be plated. Then the entire body128 is subject to electroplating, but the plating only “takes” to theouter parts 128 a and 128 b.

In an alternative embodiment of the bracket 30, FIG. 25, the springcontacts 132 are replaced by a plug 136 of a standard plug and socketconnector and the conductive coatings on the body 128 extend onto theplug 136.

In a modification of the above embodiment, the body 128 could comprisemore than two independently plated parts 128 a, and 128 b, e.g. threesuch parts each subtending an angle of about 120 degrees at the centreand each insulated from the others. In such a case two of the partswould provide power and ground connections for the PCB, while the thirdpart could provide a data connection to other equipment mounted in themirror housing.

Alternatively, FIG. 26, the data connection could be provided by a solidconductor 134 c embedded in and extending the full length of the centralpart 128 c. The surface of the conductor 134 c exposed at the lower endof the part 128 c could be slidingly engaged by a further spring contactextending from the lead frame, similar to the contacts 102 a, 102 b. Inall embodiments of bracket, however, cooperating stop means (not shown)on or in the ball member 33 and socket member 32 respectively aredesigned to limit the degree of angular adjustment of the mirror toensure that each spring contact remains in engagement with itsrespective contact on the lower end of the body 128.

The invention is not limited to the embodiments described herein whichmay be modified or varied without departing from the scope of theinvention.

1. An interior rearview mirror assembly for a vehicle, said interiorrearview mirror assembly comprising: an electro-optic mirror unit whosereflectivity is variable in response to an electrical voltage appliedthereto, said electro-optic mirror unit comprising a first substrate anda second substrate with an electro-optic medium sandwiched therebetween;said mirror unit providing a rearward field of view to a driver of avehicle when said interior rearview mirror assembly is mounted in thevehicle; said first substrate being closer to the driver of the vehiclethan said second substrate when said interior rearview mirror assemblyis mounted in the vehicle; said first substrate having a first surfaceand a second surface, said first surface being closer to the driver ofthe vehicle than said second surface when said interior rearview mirrorassembly is mounted in the vehicle, said first substrate having atransparent electrical conductor disposed at said second surface of saidfirst substrate, said first substrate having a first perimeter edgeabout a periphery of said first substrate and between said first andsecond surfaces; a bezel disposed at least partially in front of saidmirror unit and encompassing said first perimeter edge, an overlappingportion of said bezel overlapping a perimeter region of said firstsurface; said second substrate having a third surface and a fourthsurface, said third surface being closer to the driver of the vehiclethan said fourth surface when said interior rearview mirror assembly ismounted in the vehicle, said second substrate having a mirror reflectordisposed at said third surface of said second substrate, said secondsubstrate having a second perimeter edge about a periphery of saidsecond substrate and between said third and fourth surfaces; said secondperimeter edge comprising a recess that is recessed relative to acorresponding region of said first perimeter edge when said first andsecond substrates are assembled together to sandwich said electro-opticmedium therebetween, a front surface portion of said correspondingregion of said first perimeter edge being at least partially overlappedby said overlapping portion of said bezel; and at least one sensordisposed behind said first substrate and operable to receive lightthrough at least one aperture in said overlapping portion of said bezeland through said first substrate and unobstructed by said secondsubstrate.
 2. The interior rearview mirror assembly of claim 1, whereinsaid overlapping portion of said bezel is at a lower region of saidmirror unit when said mirror assembly is mounted to the vehicle.
 3. Theinterior rearview mirror assembly of claim 1 further comprising anelectrical circuit element disposed at or behind said fourth surface ofsaid second substrate.
 4. The interior rearview mirror assembly of claim3, wherein said electrical circuit element is operable to controloperation of said mirror unit in response to said at least one sensor.5. The interior rearview mirror assembly of claim 4, wherein saidelectrical circuit element is disposed at a backplate of said mirrorunit, said mirror unit being mounted to said backplate.
 6. The interiorrearview mirror assembly of claim 5, wherein said electrical circuitelement is electrically connected to said mirror unit by contactsextending out of said backplate.
 7. The interior rearview mirrorassembly of claim 5, wherein said backplate includes a support forpivotally mounting said mirror unit in the vehicle.
 8. The interiorrearview mirror assembly of claim 1 further comprising a bracket forsupporting said rearview mirror assembly from an interior portion of thevehicle.
 9. The interior rearview mirror assembly of claim 8, whereinsaid bracket connects to said mirror unit via a ball and socket pivotassembly, said ball being fixed relative to said bracket and said socketbeing fixed relative to said mirror unit.
 10. The interior rearviewmirror assembly of claim 9, wherein said pivot assembly includes aplurality of electrical contacts and counter-contacts for supplyingelectrical power to an electrical circuit element of said mirrorassembly from a vehicle electrical system external to said mirrorassembly, the power being provided to said electrical circuit elementover a range of angular movement of said mirror unit relative to saidbracket.
 11. The interior rearview mirror assembly of claim 10, whereinsaid ball comprises a convex surface, said electrical contacts beingdisposed at said convex surface.
 12. The interior rearview mirrorassembly of claim 1, wherein said electro-optic mirror unit comprises anelectrochromic mirror unit.
 13. The interior rearview mirror assembly ofclaim 1, wherein said first substrate is substantially the same size assaid second substrate.
 14. The interior rearview mirror assembly ofclaim 1, wherein said first substrate is offset relative to said secondsubstrate.
 15. An interior rearview mirror assembly for a vehicle, saidinterior rearview mirror assembly comprising: an electro-optic mirrorunit whose reflectivity is variable in response to an electrical voltageapplied thereto, said electro-optic mirror unit comprising a firstsubstrate and a second substrate with an electro-optic medium sandwichedtherebetween; said mirror unit providing a rearward field of view to adriver of a vehicle when said interior rearview mirror assembly ismounted in the vehicle; said first substrate being closer to the driverof the vehicle than said second substrate when said interior rearviewmirror assembly is mounted in the vehicle; said first substrate having afirst surface and a second surface, said first surface being closer tothe driver of the vehicle than said second surface when said interiorrearview mirror assembly is mounted in the vehicle, said first substratehaving a transparent electrical conductor disposed at said secondsurface of said first substrate, said first substrate having a firstperimeter edge about a periphery of said first substrate and betweensaid first and second surfaces; said second substrate having a thirdsurface and a fourth surface, said third surface being closer to thedriver of the vehicle than said fourth surface when said interiorrearview mirror assembly is mounted in the vehicle, said secondsubstrate having a mirror reflector disposed at said third surface ofsaid second substrate, said second substrate having a second perimeteredge about a periphery of said second substrate and between said thirdand fourth surfaces; said second perimeter edge comprising a recessededge portion that is recessed relative to a corresponding edge portionof said first perimeter edge when said first and second substrates areassembled together to sandwich said electro-optic medium therebetween;and at least one sensor disposed behind said first substrate andgenerally at said recessed edge portion, said at least one sensor beingoperable to receive light through said first substrate and unobstructedby said second substrate.
 16. The interior rearview mirror assembly ofclaim 15 further comprising a bezel disposed at least partially in frontof said mirror unit and encompassing said first perimeter edge, anoverlapping portion of said bezel overlapping a perimeter region of saidfirst surface and being disposed in front of said at least one sensor.17. The interior rearview mirror assembly of claim 16, wherein said atleast one sensor is operable to receive light through at least oneaperture in said overlapping portion of said bezel.
 18. The interiorrearview mirror assembly of claim 16 further comprising a housing, saidbezel retaining said mirror unit in said housing.
 19. An interiorrearview mirror assembly for a vehicle, said interior rearview mirrorassembly comprising: an electrochromic mirror unit whose reflectivity isvariable in response to an electrical voltage applied thereto, saidelectrochromic mirror unit comprising a first substrate and a secondsubstrate with an electrochromic medium sandwiched therebetween; saidmirror unit providing a rearward field of view to a driver of a vehiclewhen said interior rearview mirror assembly is mounted in the vehicle;said first substrate being closer to the driver of the vehicle than saidsecond substrate when said interior rearview mirror assembly is mountedin the vehicle; said first substrate having a first surface and a secondsurface, said first surface being closer to the driver of the vehiclethan said second surface when said interior rearview mirror assembly ismounted in the vehicle, said first substrate having a transparentelectrical conductor disposed at said second surface of said firstsubstrate, said first substrate having a first perimeter edge about aperiphery of said first substrate and between said first and secondsurfaces; said second substrate having a third surface and a fourthsurface, said third surface being closer to the driver of the vehiclethan said fourth surface when said interior rearview mirror assembly ismounted in the vehicle, said second substrate having a mirror reflectordisposed at said third surface of said second substrate, said secondsubstrate having a second perimeter edge about a periphery of saidsecond substrate and between said third and fourth surfaces; said secondperimeter edge comprising a recessed edge portion that is recessedrelative to a corresponding edge portion of said first perimeter edgewhen said first and second substrates are assembled together to sandwichsaid electrochromic medium therebetween; and at least one sensordisposed behind said first substrate and generally at said recessed edgeportion, said at least one sensor being operable to receive lightthrough said first substrate and unobstructed by said second substrate.20. The interior rearview mirror assembly of claim 19, wherein said atleast one sensor is operable to receive light through at least oneaperture in a bezel of said mirror assembly.